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From: Oliver Upton <oupton@kernel.org>
To: Leonardo Bras <leo.bras@arm.com>
Cc: kvmarm@lists.linux.dev, Marc Zyngier <maz@kernel.org>,
	Joey Gouly <joey.gouly@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Wei-Lin Chang <weilin.chang@arm.com>,
	Steffen Eiden <seiden@linux.ibm.com>
Subject: Re: [PATCH 11/22] KVM: arm64: Use a struct for stage-1 walk context
Date: Wed, 23 Sep 2026 13:23:22 -0700	[thread overview]
Message-ID: <arQ1OiEQjAtWwiDy@kernel.org> (raw)
In-Reply-To: <arQGa54nNYBokQ8F@LeoBrasDK>

On Wed, Sep 23, 2026 at 06:03:39PM +0100, Leonardo Bras wrote:
> > @@ -482,15 +490,15 @@ static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
> >  	while (1) {
> >  		u64 index;
> >  
> > -		va_bottom = (3 - level) * stride + wi->pgshift;
> > +		va_bottom = (3 - ws.level) * stride + wi->pgshift;
> >  		index = (va & GENMASK_ULL(va_top, va_bottom)) >> (va_bottom - 3);
> >  
> > -		ipa = baddr | index;
> > +		ws.desc_ipa = ws.desc_pa = baddr | index;
> >  
> >  		if (wi->s2) {
> >  			struct kvm_walk_access s2_access = {
> >  				.type	= WALK_ACCESS_S1PTW,
> > -				.ia	= ipa,
> > +				.ia	= ws.desc_ipa,
> 
> I only see desc_ipa being used here, and at this point, desc_ipa is the 
> same as desc_pa, and we are copying it's value to this new struct.

This distinction is intentional, we overloaded @ipa to mean either the
IPA of the descriptor or the PA of the descriptor depending on the
presence of a stage-2 && where we are in the PTW.

I'm happy to burn another 8 bytes if it means the code is legible and
more easily debuggable with something like bpftrace.

> Reviewed-by: Leonardo Bras <leo.bras@arm.com>

Thanks!

Best,
Oliver

  reply	other threads:[~2026-09-23 20:23 UTC|newest]

Thread overview: 90+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-23 18:41 [PATCH 00/22] KVM: arm64: nv: Implement FEAT_HAFDBS, FEAT_HAFT Oliver Upton
2026-06-23 18:41 ` [PATCH 01/22] KVM: arm64: nv: Introduce struct for stage-2 walk step Oliver Upton
2026-09-21 11:30   ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 02/22] KVM: arm64: nv: Consolidate computation of stage-2 permissions Oliver Upton
2026-06-23 18:57   ` sashiko-bot
2026-09-21 13:46   ` Leonardo Bras
2026-09-21 21:28     ` Oliver Upton
2026-06-23 18:41 ` [PATCH 03/22] KVM: arm64: nv: Get rid of kvm_s2_trans*() accessors Oliver Upton
2026-09-21 16:18   ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 04/22] KVM: arm64: nv: Only shadow writable-dirty guest descs as writable Oliver Upton
2026-06-23 18:58   ` sashiko-bot
2026-06-23 20:05     ` Oliver Upton
2026-09-21 16:51   ` Leonardo Bras
2026-09-21 21:39     ` Oliver Upton
2026-06-23 18:41 ` [PATCH 05/22] KVM: arm64: nv: Pass an access descriptor for stage-2 walks Oliver Upton
2026-06-23 19:06   ` sashiko-bot
2026-09-21 17:28   ` Leonardo Bras
2026-09-21 21:45     ` Oliver Upton
2026-09-22 14:24       ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 06/22] KVM: arm64: nv: Use a helper for stage-2 descriptor updates Oliver Upton
2026-09-22 16:14   ` Leonardo Bras
2026-09-22 16:31     ` Oliver Upton
2026-06-23 18:41 ` [PATCH 07/22] KVM: arm64: nv: Set dirty state at stage-2 Oliver Upton
2026-06-23 19:03   ` sashiko-bot
2026-07-06 16:50   ` Wei-Lin Chang
2026-07-08  7:35     ` Oliver Upton
2026-09-23 14:09   ` Leonardo Bras
2026-09-23 16:46     ` Oliver Upton
2026-06-23 18:41 ` [PATCH 08/22] KVM: arm64: nv: Treat DBM as writable " Oliver Upton
2026-06-23 18:55   ` sashiko-bot
2026-06-23 20:08     ` Oliver Upton
2026-09-23 14:38   ` Leonardo Bras
2026-09-23 17:16     ` Oliver Upton
2026-09-24 17:22       ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 09/22] KVM: arm64: Compute S1 permissions as part of s1_walk() Oliver Upton
2026-09-23 15:47   ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 10/22] KVM: arm64: Plumb through access descriptor for stage-1 Oliver Upton
2026-09-23 16:21   ` Leonardo Bras
2026-09-23 20:37     ` Oliver Upton
2026-09-25 11:10       ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 11/22] KVM: arm64: Use a struct for stage-1 walk context Oliver Upton
2026-09-23 17:03   ` Leonardo Bras
2026-09-23 20:23     ` Oliver Upton [this message]
2026-09-25 11:20       ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 12/22] KVM: arm64: Create helper for stage-1 descriptor updates Oliver Upton
2026-06-23 18:55   ` sashiko-bot
2026-09-25 14:35   ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 13/22] KVM: arm64: Set dirty state at stage-1 Oliver Upton
2026-06-23 18:54   ` sashiko-bot
2026-06-26 15:49   ` Leonardo Bras
2026-06-26 16:03     ` Marc Zyngier
2026-06-29 10:38       ` Leonardo Bras
2026-06-26 17:35     ` Oliver Upton
2026-06-29 10:39       ` Leonardo Bras
2026-09-25 15:07   ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 14/22] KVM: arm64: Grant write permission when DBM is set at S1 Oliver Upton
2026-06-23 18:57   ` sashiko-bot
2026-09-25 15:18   ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 15/22] KVM: arm64: Don't update descriptors for "non-arch" access Oliver Upton
2026-09-25 15:51   ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 16/22] KVM: arm64: nv: Expose FEAT_HAFDBS Oliver Upton
2026-06-23 19:01   ` sashiko-bot
2026-09-25 15:53   ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 17/22] KVM: arm64: Set Access flag on table descriptors at stage-1 Oliver Upton
2026-06-23 20:56   ` sashiko-bot
2026-09-28 14:33   ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 18/22] KVM: arm64: nv: Set access flag on table descriptors at stage-2 Oliver Upton
2026-06-23 19:05   ` sashiko-bot
2026-06-23 20:14     ` Oliver Upton
2026-09-28 14:40   ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 19/22] KVM: arm64: nv: Expose FEAT_HAFT Oliver Upton
2026-06-23 19:05   ` sashiko-bot
2026-09-28 14:42   ` Leonardo Bras
2026-06-23 18:41 ` [PATCH 20/22] KVM: arm64: selftests: Only test AF behavior for emulated AT insns Oliver Upton
2026-09-28 16:01   ` Leonardo Bras
2026-06-23 18:42 ` [PATCH 21/22] KVM: arm64: selftests: Test AT emulation for FEAT_HAFT Oliver Upton
2026-06-23 19:05   ` sashiko-bot
2026-06-23 20:17     ` Oliver Upton
2026-09-28 17:06   ` Leonardo Bras
2026-06-23 18:42 ` [PATCH 22/22] HACK: KVM: arm64: nv: Set the dirty state for CMOs that fetch for write Oliver Upton
2026-07-01 10:16   ` Wei-Lin Chang
2026-07-01 17:33     ` Oliver Upton
2026-07-02  6:50       ` Wei-Lin Chang
2026-09-28 17:21   ` Leonardo Bras
2026-06-26 15:31 ` [PATCH 00/22] KVM: arm64: nv: Implement FEAT_HAFDBS, FEAT_HAFT Leonardo Bras
2026-06-26 17:12   ` Marc Zyngier
2026-06-26 17:45     ` Oliver Upton
2026-06-29 10:37       ` Leonardo Bras
2026-06-29 10:29     ` Leonardo Bras
2026-09-18 14:55 ` Leonardo Bras

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